Starfire

Custom Power Supply for mb6582

235 posts in this topic

Has anyone built a C-64 power supply clone, one that outputs the needed 9VAC and 5VDC. I'd like to build one but hate to reinvent the wheel if there are some good schematics out there that work well.

Thanks!

Edited by Starfire

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It's been a glimmer in my eye for a long time ... the hardest part has been finding a cost-effective transformer. I want dual 9V windings (or I suppose one 9 volt and one anywhere from 7-10 volts), at 2 amps or better.

Hammond has one (266M18), but here in Canada it's over 40 bucks just for the transformer. Add an enclosure, perfboard, 78S05 (or other high-current 5V regulator), power inlet jack and passive components like capacitors, and we're looking at a lot of money for something that should be pretty simple.

Since I have ended up with a couple defective Commodore supplies, I may even attempt to de-pot the transformers, possibly with the aid of a solvent like acetone or Bioact.

I'll jump at the opportunity if I can find a suitable transformer for around 20 bucks. Otherwise, while I'll probably get around to it eventually, it won't be a high priority for me until my MB-6582 chews through another C64 power supply...

I'm not saying that there is something wrong with MB-SID or MB-6582 that is killing my power supplies. These things are almost 30 years old, and the North American C64 power supplies are notorious for failure.

So ... how about you? How far have you looked into this?

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It's been a glimmer in my eye for a long time ... the hardest part has been finding a cost-effective transformer. I want dual 9V windings (or I suppose one 9 volt and one anywhere from 7-10 volts), at 2 amps or better.

How about something like this?

9-0-9 V transformer 20 VA

They have 160 VA (12 V minimum) and I think you can get 50 VA from http://voltelectronics.com.au

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http://shop.voltelectronics.com.au/9-9-50va-toroidal-transformer.html

Oh, shame, these are all 240 V, sorry about that. You could find a 110 V one?

How about this transformer.... still not cheap, but it won't add noise!

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=TE62062-ND

I had 3 C64 PSU crap out, and one took every single right channel sid in my MB6582 with it.

I'm using the MB808 (others have too) PSU design, but using a 12volt transformer. It's not done though so I can't swear 100% it will work, but it works real nice in my MB808...

Cheers,

grizz

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How about this transformer.... still not cheap, but it won't add noise!

http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=TE62062-ND

I had 3 C64 PSU crap out, and one took every single right channel sid in my MB6582 with it.

OUCH! That might just be the motivation I need! So sorry about your loss.

Digikey also sells a dual 9V toroid for a little cheaper than the upright hammond, and they have 17 in stock. http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=237-1337-ND

The datasheet however warns "Primary and secondary windings are designed to be connected in series or parallel. Windings are not intended to be used independently." Having never used a toroid before I'll admit this gives me the creeps a bit, since I plan to disobey this little warning. Maybe I'd be better off sticking with good ol' Canadian-made Hammond.

The Electro Sonic site (www.e-sonic.com) is down atm but the Hammond 266M18 is around $42 CAD there, with a lead time of 3 days. http://www.hammondmfg.com/266.htm

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Hello. Im in the process of designing this powersupply. I have both sids type, so the powersupply will have 5 volt max 5amp and 9 and 12volt max 1 amp each. I have a pretty good start on the design and a pretty good idea on how its gonna be.

Due to insufficient funds at the end of this month, i havent yet ordered in the transformers and i also lack some caps, but from feb 5th i will start some serious work on prototyping. I will post every bit of info on this when its ready.

So far the design features 3 transformers, one at 17vac for 12v dc regulated, 9vac for 9vdc regulated and 9vac for 5vdc regulated. The choice of sec. output voltage is based on calculations of how much the voltage is increased passing the rectifier bridge, availability of transformers and some headroom.

Each transformer will be followed by a rect.bridge of their own.

The 12 and 9 volt rails will be driven from a 2amp max 78xx (L78S09C and L78S12C if my memory is intact). The 5 volt rail will be driven from a regular 7805 and a 5amp max pass transistor or what its called, for higher current. This way the high current transistor will take on most of the load, enabling the psu to pump 5amps max to the mb6582s 5volt system. Based on calculations and experience of people who built the synth, no more than 2amps is required for 5volt, but i want to have this headroom because 1: i want to be sure it works under worst conditions like more enviormental heat than normal. The datasheet for the transistor i have in mind (tip122) states temp test condition to 25c. 2: i might find out that i want to drive more cuircuts from the same psu like midibox64e or midiboxLC for a live controller for vsti i use in addition to the sid.

Because of this i will provide a extra 5 volt output from the psu for this use in addition to a output plug with all three voltages for the mb6582.

The outputs will require some kind of transistor based current limitors to make sure the psu's outputs are protected. My plan is to protect the 9 and 12volt rails on 1 amp each. The 5 volt for sidsynth will be limited to 3 amps and the extra 5volt output limited on 1,5 amps.

Each rail will have 25v 2k to 4k uF caps after the rect.bridges. also additional caps are required around the vregs as stated in their datasheets. A good referance is TKs core8 psu schematics for caps needed.

The psu i design is meant to fit in a 19" rack. I have not yet taken the space needed for the components into account, but i take it for granted they will fit in my 3 unit box from an old pa amp i am going to gut.

This psu will require serious heat sinking for output transistors an also for the vregs. Personally i will install a fan too.

So that is about my plans for the design. I will make a work blog or something with details and pics when i start prototyping next month.

Tbreath.

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=psu]this or this might be something to consider (the latter is untested :) ). I'me a HUGE advocate for building a custom PSU. The C64 PSU is #%^!ing $^#&. People need to let that thing go :) It's not hard to build a PSU that will work for an MB-6582. It's really just a handful of parts, some care, and fuses :)

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sorry to read about the frozen sids, grizz... now i am officially scared, too, when turning on my beloved mb6582...

@technobreath: sounds great, looking forward to read more in the blog/wiki.

@m00dawg: while northernlightxs design looks great (and easy and cheap to build with reichelt partslist), it seems, that it does not provide the necessary 1+ amps for the mb6582 on the 5v chain... so the diodes, the load resistors and the vregs would have to be upgraded to higher-current versions, if i am correct (and that might not be the case, as an electronics noob i am ;-)).

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I run my MB-6582 on just a 7809 and 7805. Basically it's like his design but without the +12V since I didn't need it. But I used resistors and heatsinks for both regulators. Wasn't a problem. Many 78xx can handle above 1amp with proper heatsinks. Just look at the datasheets of the one you're going to buy to make sure. The C64 PSU has a 7805 regulator in it, in fact.

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then this indeed sounds like a cool and simple solution. thanks, m00dawg!

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What is the specs on the transformer(s) you use? Hehe, u cant run vregs off mains hehe.

78xx vregs get very hot at those currents... glad it works for you. And its nice to hear that the synth doesnt require extreme amount of power to work.

My idea is however to make a psu wich will go on and on under worst condotions. And for that i need to design a way to blow fuses in a safe way. Hence the current limiting transistor. Fuses blow too slow to protect against the shorts from the load, and the current limiter buys time for the fuse to blow before you destroy the pass transistor, vregs or the tansformer. The idea is for powersupply protection in case the synth fails and tries to draw too much current through the psu. Also when it does so it shuts down (blow the fuse) and protect the load from further damage.

A design with vregs only works as you have prooven with proper heat sinks, but if anything fails, u will most likely end up fixing the psu as well as the synth. With current limiting based on transistor you will be as safe as u can be.

A crowbar circuit may also be used instead of transistor limiter, hands up for smashtv for that tip.

Star: sorry for kinda hijacking your thread. It wasnt my purpose. I only meant to give u guys a heads up that im working on what you asked for right now... hope you get some info that is valuable to you from it.

For my blog: where is a good place to host pics online wich doesnt get deleted after only a short time? Any suggestions? Preferably a free host that is...

Tbreath

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I'm interested in your design as well. So if you ever do a PCB let me know. i Am taking one to drive my 6582 correctly :-)

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What is the specs on the transformer(s) you use? Hehe, u cant run vregs off mains hehe.78xx vregs get very hot at those currents... glad it works for you.

Oh well of course I don't run the vregs off mains. I used a 12VAC transformer. In my current design, that runs through a rectifier, caps (typical thing) and then directly to the 7809. For the 7805 I use power resistors to bring the things down before it hits the 7805. The regulators and resistors are both heatsinked.

Currently I only have a single fuse from mains to the xformer. That's really there to prevent me from doing something stupid. The +5V rail may get close to 1A but I haven't heard any reports of exceeding that (you can find more accurate numbers by searching on the wiki or forums - I forget the numbers people have ended up with for typical current draw). The +9V rail likely won't get near that (also you can find the specifics on the forums).

I forget the VA of my current xformer. For my next PSU I was going to go with the 50VA from Northern's specs as that seems more than enough. I'm not that familiar with current limiting transistors (I know Wilba does trickery there for the LED and button matrices) so that's a thought. Crowbar circuit is totally new concept to me so I'll have to do some Googling :) Resettable fuses are something to consider as well.

That said, if the regs blow I'm not that concerned. They're cheap. To some degree, even the xformer is cheap(er) compared to the precious SIDs, but I won't disagree with having more methods of protecting a circuit for sure.

The thought of a C64-compatible PSU has come up a few times here on the forums since I've been around. I haven't seen a really good "kit" for one but the design is fairly simple. I know people would love to have a nice repeatable design, if not a full blown bulk-order style kit for sure. I think the fewer C64 PSU's that are in use, the better.

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Well I went ahead and ordred this transformer: Digikey

Also got all 125degree caps for the DC side, I want this to work and last a long time! We'll see how it comes out.

I did run across this schematic of the inside of the C64 supply, although we don't need that much amperage.

post-7270-097701300 1296496450_thumb.gif

Edited by Starfire

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Well I went ahead and ordred this transformer: Digikey

Broken link - can you re-post?

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Broken link - can you re-post?

Sorry it was a link from my search, should work now.

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Sorry it was a link from my search, should work now.

Also there is this one, which has the same stats as the one I ordred but it's a PC mount, I wanted to be able to stand the coil on it's end to save some space so I got the wired version.

My link

Edited by Starfire

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Hi.

I have been looking for a good supplier for transformers, i will look into digikey's ones.

That psu schematic you link to i havent seen before, but it will not be good enough as a full featured custom psu for the mb6582 i think. It has no 12v wich is required for 6581 sids. You will also have to depend on more circuits inside the synth to work. Also i cant see its regulated in any way and as far as i can see it has no other overcurrent protection than regular fuses. I guess if this actually is a real diagram for the c64 psu some protecting circuit is designed into the c64 itself.

This design differs a lot from my design and cant be used for what i plan, but it may very well work for some boxes. I havent studied thw different psu options for the synth well enough to say if this is good enough...

Let us know how it works out with this solution and good luck :-)

Ill post a pic of my circuit later on when i figure out how to design the current limiter. Its almost finished now. If more. people are interested in the psu i should maybe try to design it with that in mind - easily available parts and a good pcb design etc...

I have no real experience with routing pcbs other than by hand with permanent marker hehe, so i should get myself a descent program for this and make a pcb design. What program do we midiboxers use for this? I could do it in ultiroute, but it aint free and i suspect most midiboxers would prefer a free alternative... ive seen there is a prog - eagle - can this be used for this?

Tbreath

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Also there is this one, which has the same stats as the one I ordred but it's a PC mount, I wanted to be able to stand the coil on it's end to save some space so I got the wired version.

My link

Hmmm, your original link still doesn't work for me!

But the problem with the TE2257-ND is that a single winding provides only 1.38 amps. Also, with a toroid, I am concerned about the different loading on the two windings. Admittedly I don't have experience with such things, so I hope it works perfectly for you. It certainly would be a nice option. Keep us posted!

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@technobreath:

The C64 (and MB-SID in "optimized psu" configuration) adds the regulated 5VDC and unregulated 9VAC, then regulates the result at 12 VDC to power the 6581.

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Well been trying to get on here for a while, damn DNS problem, anyhow I got my parts and threw the power supply together and it works fine, I can't really run my mb-6582 as I am waiting for my front panel to finish it but I hooked it up and correct powers are seen on the base board for the 5v, 9v, and 12v, ran all the PICs and SIDs without any issue. I'll have to see when I finish it all, but I really think it'll be fine.

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You guys still messin' with my PSU desing huh? :)

Sad to say I never got it working and all MB stuff has been in the closet for several years. Would love to finish that stuff one day, but I don't have them skillz to finally make a usable PSU. Anybody in the Amsterdam / Haarlem area willing to help? (read: I'll provide coffee/beer and/or entertainment while you do the hard work, and I will offer spare parts/ICs/other cool stuff as compensation for your time).

Cheers, NLX

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A shame you didn't get it working - and a HUGE shame your MidiBox projects in the closet! Very sad!

Your PSU design seems pretty solid on paper. I made a few changes (mostly with layout) but I think it's pretty good. I had a similar design for my MB-6582 (without the bi-polor option) using power resistors to bring the voltage down before the 7805 and it worked very well.

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I made this one:

http://www.midibox.org/dokuwiki/doku.php?id=bipolar_12v_psu&s[]=psu

and then a separate 5V psu.

Used these transformers:

https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=56-200-67&toc=0

https://www.elfa.se/elfa3~eu_en/elfa/init.do?item=56-200-26&toc=0

They are very small and neat. I fit the PSU, 4xAOUT_NG, 4xSSM2044 and 2xSSM2164 in a 1U rack unit. It is not 100% finnished yet though, but I have verified the PSU.

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